Astronomy Seminar of the Week (2012 April 29)

2012, Week 18

Audio: Part 1 (MP3, 29Mb), Part 2 (MP3, 28Mb)
Dark Mysteries: What is the Universe Made of?
Presenter: Dr. George Djorgovski
MICA Director, Professor of Astronomy and Co-Director of the Center for Advanced Computing Research at Caltech

One of the key goals of the science of cosmology is to determine the matter and energy contents of the universe; they, in turn, determine its ultimate fate – whether it will expand forever, or recollapse into a reverse of the big bang, a “big crunch.” A great progress has been made in this field over the past decade. We now know that about 70% of the total matter/energy content of the universe is a mysterious “dark energy,” which drives an accelerated expansion, and whose physical nature remains unknown. Another 25% or so is dark matter, whose nature is also unknown, but whose gravitational effects can be measured very well. Only about 5% of the total content is the matter we know, composed of atoms and known particles. We describe how cosmologists know these things, and what are they doing to help resolve these outstanding mysteries of science.
First presented in Second Life in September, 2008.

Questions and comments can be posted on the discussion thread on Starship Asterisk; Dr. Djorgovski will answer a selection of questions posted by May 13, 2012.

PDF of slides (21Mb)

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